Why is it that when I add a movie that is already in the database, it would still ask the user to key in an input instead of displaying "The movie already already exist"

movies = {
'17 Miracles' => 10,
'Superman' => 10
}
puts "What would you like to do?"
puts "Please type one of the following according to your choice"
puts "add - Add a movie"
puts "update - Update a movie in the database"
puts "display - Display a movie of your choice"
puts "delete - Delete a movie in the database"
choice = gets.chomp
case choice
when 'add'
puts "What movie do you want to add?"
title = gets.chomp
if movies[title.to_sym].nil?
puts "What's the rating? (Type a number 0 to 4.)"
rating = gets.chomp
movies[title.to_sym] = rating.to_i
puts "#{title} has been added with a rating of #{rating}."
else
puts "That movie already exists! Its rating is #{movies[title.to_sym]}."
end
when "update"
puts "Enter the movie title:"
title = gets.chomp
if movies[title].nil?
puts "The movie is not yet added in the database"
else
puts "Enter the new movie rating:"
rating = gets.chomp
movies[title.to_sym] = rating.to_i
end
when "display"
movies.each do |movie, rating|
puts "#{movie}: #{rating}"
end
when "delete"
puts "What movie would you like to delete?"
title = gets.chomp
if movies[title].nil?
puts "The movie is not yet in the database"
else
movies.delete(title.to_sym)
puts "#{title} has been removed from the database"
end
else
puts "Error!"
end